1. Field of Invention
The present invention relates to fuel injection control apparatuses for an internal combustion engine.
2. Description of Related Art
In existing systems, in order to suppress overheating of a catalyst bed temperature (“bed temperature”) of an exhaust converting catalyst depending on an operation state of an internal combustion engine, fuel injection amount is increased based not only on an amount of heat supplied to the catalyst from exhaust gas but also on an amount of heat generated due to the catalytic reaction.
However, at the time of fuel cut control or a rapid decrease in intake air amount, the fuel adhering to the wall surfaces of a fuel injection port of an intake passage (“wall flow”) may flow into the catalyst in an unburned state. As a result, estimation accuracy of the catalyst bed temperature may decrease, or the catalyst bed temperature may become excessively high, depending on the wall flow amount.
An object of the present invention is to provide a fuel injection control apparatus for an internal combustion engine which is capable of accurately estimating the catalyst bed temperature even when the wall flow amount of the fuel injection port fluctuates, or of preventing overheating of the catalyst bed temperature.